A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single, specific day within such a system. A calendar is also a physical record (often paper) of such a system. A calendar can also mean a list of planned events, such as a court calendar or a partly or fully chronological list of documents, such as a calendar of wills.

Calendaring software is software that minimally provides users with an electronic version of a calendar. Additionally, the software may provide an appointment book, address book, and/or contact list. These tools are an extension of many of the features provided by time management software such as desk accessory packages and computer office automation systems. Calendaring is a standard feature of many PDAs, EDAs and smartphones and also of many office s…